.flex_content () {
  display: -webkit-box;  /* 老版本语法: Safari, iOS, Android browser, older WebKit browsers. */
  display: -moz-box;     /* 老版本语法: Firefox (buggy) */
  display: -ms-flexbox;  /* 混合版本语法: IE 10 */
  display: -webkit-flex; /* 新版本语法: Chrome 21+ */
  display: flex;         /* 新版本语法: Opera 12.1, Firefox 22+ */
}

.flex_one () {
  -webkit-box-flex: 1;  /* OLD - iOS 6-, Safari 3.1-6 */
  -moz-box-flex: 1;     /* OLD - Firefox 19- */
  -webkit-flex: 1;      /* Chrome */
  -ms-flex: 1;          /* IE 10 */
  flex: 1;              /* NEW, Spec - Opera 12.1, Firefox 20+ */
}

.flex_column (){
  webkit-box-orient: vertical;
  -webkit-flex-direction: column;
  -ms-flex-direction: column;
  flex-direction: column;
}

.flex_align_center (){
  -webkit-box-align: center;
  -webkit-align-items: center;
  -ms-flex-align: center;
  align-items: center;
}
.flex_justify_center(){
  -webkit-box-pack: center;
  -webkit-justify-content: center;
  -ms-flex-pack: center;
  justify-content: center;
}
.flex_justify_space(){
  -webkit-box-pack: justify;
  -webkit-justify-content: space-between;
  -ms-flex-pack: justify;
  justify-content: space-between;
}
.flex_justify_end(){
  -webkit-box-pack: end;
  -webkit-justify-content: flex-end;
  -ms-flex-pack: end;
  justify-content: flex-end;
}
// 从左到右
.linear_gradient_back (@color1, @color2){
  background: -webkit-linear-gradient(left, @color1, @color2); /* Safari 5.1 - 6.0 */
  background: -o-linear-gradient(right, @color1, @color2); /* Opera 11.1 - 12.0 */
  background: -moz-linear-gradient(right, @color1, @color2); /* Firefox 3.6 - 15 */
  background: linear-gradient(to right, @color1, @color2); /* 标准的语法（必须放在最后） */
}
// 从上到下
.linear_gradient_back_top (@color1, @color2){
  background: -webkit-linear-gradient(@color1, @color2); /* Safari 5.1 - 6.0 */
  background: -o-linear-gradient(@color1, @color2); /* Opera 11.1 - 12.0 */
  background: -moz-linear-gradient(@color1, @color2); /* Firefox 3.6 - 15 */
  background: linear-gradient(@color1, @color2); /* 标准的语法（必须放在最后） */
}
// box-shadow
.box-shadow(@x: 0; @y: 0; @blur: 1px; @color: #000) {
  -webkit-box-shadow: @arguments;
  -moz-box-shadow: @arguments;
  box-shadow: @arguments;
}